Recent content by sweetreason

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    How can I calculate the time it would take for my battery to run down?

    Nascent, I got the resistance figure from the parts store I'm looking at. The specs of the part are http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=5382. The same page says the max voltage is 15 V. I'd guess the motors are giong to be in parallel, but I'm not really sure...
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    How can I calculate the time it would take for my battery to run down?

    I don't actually have the all the components in front of me, I'm trying to determine how the components will drain the battery before I buy the components. So I can't test the circuit, I've got to calculate it.
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    How can I calculate the time it would take for my battery to run down?

    gneill, how do I do that? can I use V=IR with V as the battery voltage and R the total resistance in the circuit?
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    How can I calculate the time it would take for my battery to run down?

    Sorry, I should have included that information. The capacity of the battery is 1800mah. But how do I use this information? Wouldn't I first need to figure out how much current my circuit elements are drawing? How do I find that? I know the resistance (573 Ohms x 4 elements) and there is a power...
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    How can I calculate the time it would take for my battery to run down?

    This isn't actually a homework/schoolwork question, but all the stickies on the other boards say that anything that is a school-work *type* question should go here. Not sure if this qualifies, but I figured I'd err on the side of caution. I took physics II last year and now I'm trying to do a...
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    Linear Differential Equation: Dropping Absolute Value Bars

    Well, I know the absolute value bars are there to extend the domain of the natural log function, which normally only has domain (0, +infinity). I guess what you're implying is that since e^{\ln x} = e^{\ln|x|} this implies x = |x|, or x \geq 0 ? Is that right?
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    Linear Differential Equation: Dropping Absolute Value Bars

    I'm doing some practice problems, and with the help of my solutions manual and wolfram alpha I've worked out a solution to (x+1)\frac{dy}{dx} +xy = e^{-x} However, I don't understand why we can drop the absolute value bars when we calculate the integrating factor: e^{\int...
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    Theory question - Blackbody Radiation and Light

    "Theory" question -- Blackbody Radiation and Light I am trying to understand the discussion about blackbody radiation in my Modern Physics textbook. (I'll quote it, but it can be found http://phy240.ahepl.org/Chp3-QT-of-Light-Serway.pdf" , page 5 document numbering, 69 textbook numbering)...
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    Why Use the Average Earth-Sun Distance in Stefan's Law for Energy Conservation?

    To make my second question a bit more precise, how can the total power emitted by the sun equal the total power received at the Earth, since presumably at least half of the power radiated by the Sun goes off in a direction opposite the Earth?
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    Why Use the Average Earth-Sun Distance in Stefan's Law for Energy Conservation?

    I am trying to understand an example in my Modern Physics textbook (Example 3.1, page 5 in thishttp://phy240.ahepl.org/Chp3-QT-of-Light-Serway.pdf" or pg 69 using the book numbering) I don't understand why the average earth-sun distance is being used in the conservation of energy equation...
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    Inductive Proof (+linear equation in four variables)

    In case you're curious, for the inductive step just add one to both sides of your induction hypothesis, then factor out 2's to obtain the desired expression.
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    Inductive Proof (+linear equation in four variables)

    I managed to prove this using induction, actually. It's a lot easier if you prove an additional base case (n=6) and then prove it for n >=7. I am still curious as to how to solve for those variables though.
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    Inductive Proof (+linear equation in four variables)

    Homework Statement I'm trying to prove by induction that \forall n \geq 5, \exists m_1, m_2 \in \mathbb{N} such that n = 2m_1 +3m_2. Homework Equations (none, really) The Attempt at a Solution I've done the base case, and the inductive step boils down to showing that \exists...
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    Inductive Proof (+linear equation in four variables)

    I'm trying to prove by induction that \forall n \geq 5, \exists m_1, m_2 \in \mathbb{N} such that n = 2m_1 +3m_2. I've done the base case, and the inductive step boils down to showing that \exists m_1 \prime m_2 \prime such that 2m_1 +3m_2 +1 = 2m_1 \prime +3m_2 \prime . Maybe I'm forgetting...
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